Remove network-dependent test
Bug: https://bugs.gentoo.org/921925
--- a/data/meson.build
+++ b/data/meson.build
@@ -50,11 +50,6 @@ appstream_file = i18n.merge_file(
 )
 
 appstream_util = find_program('appstream-util', required: false)
-if appstream_util.found()
-  test('Validate appstream file', appstream_util,
-    args: ['validate', appstream_file.full_path()]
-  )
-endif
 
 configure_file(
   input: '@0@.gschema.xml.in'.format(PROJECT_RDNN_NAME),